The inquest heard from a series of witnesses who all drove past Taunton on the motorway within an hour of the crash.

Lorry driver John Krostovnikoff was heading to Staffordshire from Exeter when he suddenly hit a wall of thick fog just after 7pm in the Taunton area.

"My visibility was clear and suddenly I was driving through... like a wall, then two seconds later I was through it," he said.

"I took my foot off the gas. If I braked hard and there was someone behind, you might have caused an accident.

"Two seconds in and out and I thought no more of it. It was unusual because you normally see it coming but it was clear, then like going through a wall - it was very dense."

Sainsbury's deliver driver Ian Thorne was returning to his depot in Taunton when he hit a wall of thick smoke 200 yards long just a few minutes before the fatal crash.

"It wasn't very good visibility," he said.

"I could see fireworks and then I could see the smoke they were giving off and I could see it was going to the direction of the motorway.

"It was white but I could see through it but I could also see it was 200 yards thick. It smelt of gunpowder."

Carnage: 30 vehicles were involved in the incident near Junction 25 of the M5 near Taunton, in November 2011

Luke Allen, who works as a handyman for Avon and Somerset Police, joined the northbound carriageway of the motorway at Junction 25 about an hour before the crash.

"As I joined the motorway it was fine. Not far from joining the motorway there was a wall of mist or fog right in front of me," he told the inquest.

"It was a like a white blanket... a curtain. It was like a white curtain in front of you appearing to be right across the carriageway.

"It was a dense white substance and I slowed down by decelerating. It took three to five seconds to pass through."

Mr Allen added: "It was like white emulsion, pure white. I remember thinking to myself that it didn't have any odour.

"You were in it and out of it and back to normal."

Michael Barton and his daughter Maggie, Tony and Pamela Adams, Malcolm Beacham, and lorry drivers Terry Brice and Kye Thomas, all lost their lives as smoke engulfed the carriageway near Taunton in Somerset.

Following that verdict, Mr Counsell said he believed the decision to prosecute him was "motivated by a desire to find someone to blame for this terrible accident, simply for the sake of doing so".

He had originally been charged with manslaughter but those charged were dropped. He was then accused of failing to ensure public safety.

Mr Justice Simon ruled Mr Counsell had "no case to answer" following an application from the defendant's barrister at the halfway point in the trial.

He said the prosecution's case was "heavily weighted" on "hindsight" and there was not sufficient evidence to show that Mr Counsell ought to have foreseen that smoke from the display could have drifted and mixed with fog to create thick smog.

The inquest, which is being held in front of a jury, is expected to last a week.